1. Field of the Invention
The present invention relates generally to a steering system for vehicles. More particularly, the invention relates to a steering system for vehicles of the type in which, in addition to having front wheels which are steerable, the rear wheels are steered in accordance with a travelling state representative quantity of the vehicle.
2. Description of Relevant Art
There have already been proposed a number of steering systems, for vehicles of the type in which, in addition to having front wheels which are steerable, the rear wheels are steered in accordance with a travelling state representative quantity of the vehicle.
For example, in UK patent application GB No. 2,083,422 A published on Mar. 24, 1982, there is disclosed in FIG. 1 thereof a steering system for vehicles in which, to cancel the influence of side winds to the vehicle while travelling, rear wheels are steered on the basis of detected values of the lateral acceleration of the vehicle.
With such a steering system, the maneuverability of the vehicle is favorably improved. However, in addition to the side wind there are other disturbances effecting the vehicle while travelling, such as undulations of the road surface. It is thus preferable to have the rear wheels steered taking into account such factors, whereas it is more preferable to consider the vehicle speed as well, which speed has an effect on the degree of the influence of such disturbances.
The present invention further improves such a conventional steering system for vehicles as described above.